This proposal describes a five-year program for research on the economic determinants of female headship in the U.S. which extends, broadens, and follows up in specific ways, three areas of work on the same subject by the P.I. in his prior award. One part of that prior work focused on estimation of the effects of the U.S. welfare system on female headship, and found that the results in the existing literature are substantially overturned when state fixed effects are introduced into an econometric model of headship. The present proposal describes an extended investigation into the nature of state fixed effects, their relationship to individual fixed effects, and the way in which such effects interact with dynamics and lags in the individual behavior surrounding movements into and out of headship. The proposed new analysis will also introduce male and female wage variables into the model and will investigate their relation to state and individual fixed effects. A second part of the prior work focused on estimating the dynamics of movements into and out of headship, and how the life cycle pattern of headship has been changing over time in the U.S. That analysis revealed the methodological importance of left-censoring and the substantive importance of different types of headship that occur at different points in the life cycle. The proposed new analysis will incorporate state and fixed effects into this dynamic model, as well as, more generally investigate influences of welfare benefit,s and wages. A third part of the prior work concerned the extent of cohabitation among women on AFDC and how detailed AFDC rules concerning cohabitation and marriage affect family structure. Further analysis of those incentives will be conducted. A telephone survey of AFDC welfare departments on cohabitation regulations, conducted under the first award, will be repeated in the proposed project as well.